Such hose clamps are well known and normally used to fix a hose made of plastic or rubber materials to another part, such as tubes, pipes, nipples made from plastic or metallic materials. The mechanism for increasing or reducing the effective length of the strap may typically comprise a housing with a drivable bolt or screw having an exterior thread. This housing is fixed to one end of the strap.
The place where the clamp will be assembled over is comprehended by the hose assembled over the tube, pipe or nipple. This assembly will be from now on called set.
The other end of the strap is overlying the foresaid fixed end and guided through said housing having engagement means provided in this end of the strap for engaging and is driven by the thread of the bolt or screw. For example, these engagement means may be provided by a threaded area, by teeth or several successive openings in the strap.
When rotating the bolt or screw over the set, the effective length of the strap and thus the inner free diameter of clamp may be increased or reduced depending on the direction of rotation. Having that the hose is made of elastomeric material (rubber or plastic or the like), it can be assembled to another part (i.e. tube, pipe or nipple) and fixed by means of a hose clamp surrounding the hose.
The mechanism described above will not limit the invention and only serves as an example. It is well know to the person skilled in the art to provide other mechanisms for tightening or tensioning hose clamps.
As a problem it is well known that the elastomeric material of a hose may deteriorate by aging. For example it may shrink which may cause failure of the hose connection. To reduce this risk it is known in the art to provide a spring action within a hose clamp for compensation.
For example U.S. Pat. No. 5,309,607 and U.S. Pat. No. 5,115,541 disclose a spring element mounted in the interior of such a well known hose clamp on the inner side of the unitarily formed strap. This spring element exerts a spring force in a radial direction to a hose surrounded by such a hose clamp. The disadvantage of such a spring element in the interior of the hose clamp is that the inner free diameter is artificially reduced and the cross section of the hose clamp is no more circular. Accordingly a specific area of a clamped hose which is facing the inserted spring element is more stressed than other areas of the hose leading to the problem that the elastomeric material in this area will receive a higher force and will tend to flow away which may also cause failure of the hose connection.